/*
 * Copyright (C) 2006-2007 Eskil Bylund
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

using System.IO;
using System.Threading;
using System.Security.Cryptography;

namespace DCSharp.Hashing
{
	/// <summary>
	/// A class that creates a HashTree from a file.
	/// </summary>
	public abstract class Hasher
	{
		#region Properties

		/// <summary>
		/// Gets the number of bytes that remains to be hashed.
		/// </summary>
		/// <value>The number of bytes that remains to be hashed.</value>
		public abstract long BytesRemaining
		{
			get;
		}

		#endregion

		#region Methods

		/// <summary>
		/// Creates a HashTree from a file.
		/// </summary>
		/// <param name="fileInfo">The file to create the HashTree from.</param>
		/// <param name="abortHashingEvent"></param>
		/// <returns>The HashTree from the file.</returns>
		public abstract HashTree Hash(FileInfo fileInfo,
			ManualResetEvent abortHashingEvent);

		/// <summary>
		/// Creates a Hasher instance.
		/// </summary>
		/// <param name="algorithm">The hash algorithm to use.</param>
		/// <returns>A new Hasher instance.</returns>
		public static Hasher Create(HashAlgorithm algorithm)
		{
			return new HasherManaged(algorithm);
		}

		#endregion
	}
}
